1. Field of the Invention
The present invention relates to a method of controlling a biped walking robot, and more particularly, to a method of controlling a biped walking robot to walk stably with proper balance.
2. Description of the Related Art
In a conventional biped walking robot, walking pattern data (hereinafter, referred to as waking posture data) is previously input, and walking control is based on the walking posture data. Therefore, two legs are operated according to the walking control, so that a biped gait is achieved.
In the conventional biped walking robot, the biped gait is likely to be unstable according to ground conditions, physical parameters of the robot, etc. Further, sometimes the robot may fall.
The walking control may be based on a real-time situation of the robot without previously inputting the walking posture data. However, in spite of the real-time situations, the robot may fall because of an unexpected factor such as the ground condition, etc.
To make the biped gait stable, the robot is required to be compensated with a ZMP (zero moment point) in which the resultant moment of ground reaction force and gravity force acting on a sole of a robot foot is equal to zero. As an example of the ZMP compensation, there has been disclosed a control method for the ZMP compensation in Japanese Patent Publication No. 1993-305586, in which the ZMP compensation is achieved using compliance control by moving a robot upper body and by modifying a position on which the robot foot is put.
The ground reaction force acting on the robot foot is exemplarily measured by a strain gauge load cell in which a strain gauge is attached to an elastic body which may be strained by an external force, wherein the strain gauge forms a part of a Wheatstone bridge circuit. Here, the strain gauge load cell transforms the external force into an electric signal. However, such a load cell should be accurately manufactured and requires relatively many additional circuits, so that the strain gauge load cell is mainly employed for a structure receiving a relatively large force and is not suitable for a small structure such as a walking robot.